Was the U.S. duped into striking Syria? No. The grisly deaths this week of women and children in what looks to be a chemical weapons attack was not carried out by opponents of President Trump in his own government - the, quote, unquote, "deep state." But that is the rumor that's been circulating on social media. And of course, this isn't the first time rumors like that have spread. Kate Starbird studies the spread of rumors. She teaches at the University of Washington, and her research traces fake news back past this presidential race to at least the 2013 Boston Marathon bombing.

KATE STARBIRD: We found a couple of different kinds of rumors, and one of them - there was this weird little rumor. It was kind of small but very different from the other ones and that was this theory that the Navy SEALs had perpetrated the Boston Marathon bombings. And they had been blamed on these what they called patsies, which were the suspects that were the Chechnya brothers. But it was all part of this - it was a false flag that the U.S. government or some elements of the U.S. government had perpetrated this event on itself.

GARCIA-NAVARRO: What do we see happen when a tragedy occurs? Is this - did you find that this was common?

STARBIRD: We did see across all of the manmade disaster events, over and over again, these same claims go from, you know, event to event to event.

GARCIA-NAVARRO: What we've just seen now on the strike on Syria, saying that somehow these were actors staging the event to sort of dupe the United States to make them - to draw them into the war. It's the same kind of thing.

STARBIRD: Exactly. So as soon as I saw this event, I actually posted on Facebook. I said, you know, you're seeing these images. But within, you know, a couple hours or maybe a day, you're going to see claims that this didn't really happen or that it was perpetrated by someone else. And of course, that comes to fruition.

GARCIA-NAVARRO: So the question is, so if we're seeing the same thing happening over and over again, who's doing this?

STARBIRD: I think you have people that are doing it for individual reasons. They have some political motivation, or they have financial motivation. They can make money selling these ideas, selling ads on their website.

GARCIA-NAVARRO: Just trying to get eyeballs so that they can sell, you know, whatever product they're pushing.

STARBIRD: So there's that element. Then there's people that are sincere believers in this stuff. They really - they're bought in. They think about this. They're 9/11 truthers (ph). They're JFK conspiracy theorists. And then there was elements of what seemed to be purposeful disinformation strategies. So someone who doesn't believe these things, who's got a political motivation for injecting very confusing ideas that are anti-globalist, anti-corporatist, anti-mainstream media.

And they - a lot of the theories had this idea that there's a group of very powerful people that are outside of government that sort of orchestrate things. Those are the kinds of things that were actually much more problematic than the folks that were doing it for money or the sincere believers.

GARCIA-NAVARRO: What does this say to you? What have you learned through looking at this?

STARBIRD: I've learned a lot in the last few months. So, you know, I come from computer science and media studies, but I'm really sort of an engineer background. And I've ended up in this very politicized space looking for sort of a U.S. right versus left kind of spectrum, and that's not what I found.

What I found was these kinds of theories and this way of thinking about the world is appealing to both people on the left and the right - that people are going to see one theory. Like, they're anti-vaccine or they're anti-GMO. And they're getting drawn into these other theories of, you know, deep state actors that are changing world events to manipulate you. And then getting pulled into this worldview that is very potentially dangerous.

GARCIA-NAVARRO: That's Kate Starbird. She teaches at the University of Washington. And she studies the spread of misinformation online, a huge problem these days. Thanks so much for joining us.